Selank is the heptapeptide Thr-Lys-Pro-Arg-Pro-Gly-Pro, an analogue of the immune peptide tuftsin with a Pro-Gly-Pro extension added for stability. In rodent studies it was associated with less anxiety-like behaviour, changes in genes linked to GABA signalling, effects on BDNF and on the expression of inflammation-related genes.
For research purposes only. Not for human consumption. This article is educational and references published laboratory research; it is not medical advice and does not describe an approved use of any compound.
Evidence grade
- Grade BSelank
More than five controlled rodent studies plus three small comparative clinical studies published in Russian journals. No placebo-controlled trials in international journals.
Selank is a short synthetic peptide developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, and it is often discussed alongside Semax, which came from the same institute. Most of what is published about it appears in Russian journals. This guide sets out where Selank comes from, how its mechanism is described, what was observed in rodents and in small clinical studies, and where the evidence stops.
Where does Selank come from?
Selank was developed at the Institute of Molecular Genetics in Moscow as a more stable version of tuftsin. Tuftsin is a natural tetrapeptide, Thr-Lys-Pro-Arg, cut from the heavy chain of immunoglobulin G and known for its effects on phagocytes. A 2017 review of tuftsin and its analogues describes Selank as one of the best studied of these analogues.
To make tuftsin last longer, the developers added the tripeptide Pro-Gly-Pro to its end, giving the heptapeptide Thr-Lys-Pro-Arg-Pro-Gly-Pro. The same Pro-Gly-Pro extension appears in Semax. The calculated molecular weight of Selank is about 752 g/mol.
How is it described at the molecular level?
No single receptor has been identified for Selank, and studies describe several effects. In 2001, Selank inhibited the enzymatic breakdown of enkephalins in human plasma in vitro, with an IC50 of about 15 micromolar, and was more potent in that test than the peptidase inhibitors bacitracin and puromycin. The authors linked this to their finding of shorter enkephalin half-life in people with generalised anxiety.
Later studies looked at the GABA system, because clinical observations had compared Selank to benzodiazepines. In rat frontal cortex, Selank changed the expression of 45 of 84 neurotransmission genes one hour after administration, in a pattern partly similar to GABA itself. A 2018 radioligand study found that Selank changed [3H]GABA binding as a positive allosteric modulator and proposed subtype-selective allosteric modulation of GABA receptors as one mechanism. Other studies reported changes in serotonin metabolism, BDNF levels and the expression of inflammation-related genes in mouse spleen, in line with the immune role of tuftsin.
What has been observed in published research?
- Anxiety-like behaviour under chronic stress (rat): in an elevated plus maze after unpredictable chronic mild stress, Selank reduced anxiety indicators and enhanced the effect of diazepam when the two were combined.
- Gene expression (rat): in the frontal cortex, Selank altered the expression of genes involved in GABA signalling, with changes at one hour that partly overlapped those caused by GABA.
- Memory and BDNF (rat): in rats drinking ethanol for 30 weeks, Selank was associated with better object recognition and prevented the ethanol-linked rise in BDNF in hippocampus and frontal cortex.
- Immune genes (mouse): in mouse spleen, 34 of 84 inflammation-related genes, including chemokines, cytokines and their receptors, changed in expression 6 and 24 hours after a single administration of Selank.
- Enkephalin breakdown (human plasma, in vitro): Selank inhibited enkephalin-degrading enzymes in plasma samples.
- Clinical comparisons (human, Russia): in 62 patients, Selank and medazepam showed similar anxiolytic effects on rating scales; in 60 patients, it was compared with phenazepam; in 70 patients it was added to phenazepam. These were comparative studies without placebo control.
What the evidence does not establish
Almost all Selank research comes from a small group of Russian institutes and was published in Russian or in translated Russian journals. The clinical studies were small, compared Selank with other active drugs rather than placebo, and have not been repeated in independent multicentre trials. Their results cannot be taken as established effects in people.
The mechanism remains a set of partial findings: enkephalinase inhibition at micromolar concentrations in plasma, gene expression changes in rat brain and a proposed allosteric action at GABA receptors. How these fit together, and which matter in an intact animal, has not been resolved.
Which formats does Vitality Peps supply?
Vitality Peps supplies Selank as a 10 mg lyophilised vial and as a 10 mg nasal spray format for laboratory research, each documented by a batch certificate of analysis. Bacteriostatic water is listed separately for reconstituting the vial. Researchers comparing the two Moscow peptides can find Semax in the same formats.
How is it handled in the laboratory?
Lyophilised Selank is stored cold and protected from light. Before use the vial is brought to room temperature and reconstituted with bacteriostatic water added slowly down the side, then swirled gently. The working concentration is calculated from the actual vial mass on the batch certificate. Reconstituted solution is refrigerated, labelled and dated. The nasal spray format contains a prepared solution: it is kept refrigerated and dated on opening.
Research use only
Selank supplied by Vitality Peps is for in vitro laboratory research only. Not a medicine, not a supplement, not for human or veterinary consumption. Nothing above is instructions for use.
Frequently asked questions
What is tuftsin and how is Selank related to it?
Tuftsin is a natural tetrapeptide, Thr-Lys-Pro-Arg, released from the heavy chain of immunoglobulin G and studied for its effects on immune cells. Selank keeps those four residues and adds Pro-Gly-Pro at the end. The added Pro-Gly-Pro is generally described as a stabilising extension, intended to make the short peptide last longer, while the tuftsin part is linked to its immune and nervous system activity.
How is Selank different from Semax?
Both are short synthetic peptides from the same Moscow institute and both carry a Pro-Gly-Pro extension. Semax is based on a fragment of ACTH and has been studied mainly in models of stroke and cognition. Selank is based on tuftsin and has been studied mainly in models of anxiety and stress. Some studies have examined both side by side in rats.
Has Selank been tested in human clinical trials?
Small clinical studies were published in Russian journals. One compared Selank with medazepam in 62 patients with generalised anxiety disorder or neurasthenia, another compared it with phenazepam in 60 patients, and a third combined it with phenazepam in 70 patients. None was a large placebo-controlled trial, and no trials were found in international registries or journals.
What is the enkephalin finding?
Enkephalins are natural opioid peptides that are broken down quickly by enzymes in the blood. A 2001 study found shorter enkephalin half-life in the blood of people with generalised anxiety, and Selank inhibited the breakdown of enkephalin in human plasma in vitro, with half-maximal inhibition at about 15 micromolar. The authors proposed this as one possible mechanism.
How has Selank been given in animal studies?
Rodent studies used intraperitoneal and intranasal administration, and a 2016 study compared the two routes in BALB/c and C57BL/6 mice. Vitality Peps supplies both a lyophilised vial and a nasal spray format for laboratory research, described below, without any implication of use in people.
How is Selank handled in the laboratory?
The lyophilised powder is kept cold and protected from light until use. It is reconstituted with bacteriostatic water at room temperature, and the working concentration is calculated from the actual mass on the batch certificate. The nasal spray format is a prepared solution that is refrigerated and dated on opening, as described in the storage guide.
For research purposes only. Not for human consumption. This article is educational and references published laboratory research; it is not medical advice and does not describe an approved use of any compound.
References
- Peptide-based anxiolytics: the molecular aspects of heptapeptide Selank biological activity (Protein Pept Lett, 2018)
- Tuftsin: properties and analogs (Curr Med Chem, 2017)
- The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity (Bull Exp Biol Med, 2001)
- Selank administration affects the expression of some genes involved in GABAergic neurotransmission (Front Pharmacol, 2016)
- Peptide Selank enhances the effect of diazepam in reducing anxiety in unpredictable chronic mild stress conditions in rats (Behav Neurol, 2017)
- Selank, peptide analogue of tuftsin, protects against ethanol-induced memory impairment by regulating of BDNF content in rats (Bull Exp Biol Med, 2019)
- Expression of inflammation-related genes in mouse spleen under tuftsin analog Selank (Regul Pept, 2011)
- Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia (Zh Nevrol Psikhiatr, 2008)
- A comparison of the anxiolytic effect and tolerability of selank and phenazepam in the treatment of anxiety disorders (Zh Nevrol Psikhiatr, 2014)
- Optimization of the treatment of anxiety disorders with selank (Zh Nevrol Psikhiatr, 2015)
- Peptides semax and selank affect the behavior of rats with 6-OHDA induced PD-like parkinsonism (Dokl Biol Sci, 2017)
- Comparison of pharmacological effects of heptapeptide Selank after intranasal and intraperitoneal administration to BALB/c and C57BL/6 mice (Eksp Klin Farmakol, 2016)